What is $Strigula$?

$A$ ball is allowed to fall from a height of $10\, m$. If there is $40\%$ loss of energy due to impact,then after one impact,the ball will rise to a height of ......... $m$.

The layer of cells outside the phloem meant for giving rise to the root branches is called

If $\sqrt{\frac{y}{x}}+\sqrt{\frac{x}{y}}=2$,then $\frac{d y}{d x}$ is equal to

From the following thermochemical equations,find out the heat of ionisation $Z$ for a weak acid $HA$:
$HA \to A^{-} + H^{+}$,$\Delta H = Z$
$H^{+} + OH^{-} \to H_2O$,$\Delta H = X$
$HA + OH^{-} \to A^{-} + H_2O$,$\Delta H = Y$

Statement-$I$: Two lines which pass through a given fixed point and are equally inclined to two other lines passing through the same point,are always perpendicular to each other.
Statement-$II$: Angle bisectors of two intersecting lines are always perpendicular to each other.